This shows an example of looking at signals with scopes. The analog scope on the left is hooked up to a card on an extender and to the memory backplane. The digital scope on the right is hooked up to two signals on the processor side backplane. The computer is running a teletype output toggle in test. It would be unusual to be using both scopes at once. The signals are also points picked to look good for the photo. Analog scopes show intermittent signal problems that can't be triggered on better than the inexpensive digital scopes which can't display very many traces per second. The digital scope can show the waveform prior to the trigger and easier for capturing events that happen once such as signals triggered by pressing a key. On analog scopes the trace fades away quickly unless the signal repeats to trigger again. The analog scope and the old computers keep my basement nice and warm in the winter.
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